Conserved Response Regulator CtrA and IHF Binding Sites in the α-Proteobacteria Caulobacter crescentus and Rickettsia prowazekii Chromosomal Replication Origins

CzcR is the Rickettsia prowazekii homolog of the Caulobacter crescentus global response regulator CtrA. CzcR expression partially compensates for developmental defects in ctrA mutant C. crescentus cells, and CzcR binds to all five CtrA binding sites in the C. crescentus replication origin. Conversely, CtrA binds to five similar sites in the putative R. prowazekii replication origin ( oriRp ). Also, Escherichia coli IHF protein binds over a central CtrA binding site in oriRp . Therefore, CtrA and IHF regulatory proteins have similar binding patterns in both replication origins, and we propose that CzcR is a global cell cycle regulator in R. prowazekii .